1. Machine Detector Interface
Lau Gatignon / CERN-EN

2. CLIC09 - Machine Detector Interface
Overview
Introduction to Machine Detector Interface
QD0 magnet design
QD0 stabilisation and integration
Backgrounds
Post-collision line
IP Feedback
Other items
Conclusion
L.Gatignon,
CLIC09 - Machine Detector Interface

3. CLIC09 - Machine Detector Interface
What is the MDI
The MDI is the part of the CLIC facility (approximately) inside the detector cavern, i.e. the area in which there is a strong coupling of technical sub-systems of the machine and of the physics detectors.
The lines for the spent beams shall also be considered part of the MDI.
L.Gatignon,
CLIC09 - Machine Detector Interface

4. CLIC09 - Machine Detector Interface
CLIC PARAMETERS
Parameter
ILC
CLIC
Impact on MDI
Max. Center of Mass energy [GeV]
1000
3000
Detector design,
backgrounds
Luminosity L99% [cm-2 sec-1]
2 1034
Instrumentation
Bunch frequency [Hz] 5 50
Bunch spacing [ns]
369
0.5
Background, IP feedback
# Particles per bunch
2 1010
# Bunches per pulse
2670
312
Bunch train length [ms]
985
0.156
Beam power per beam [MW] 9 14
Spent beam line
Bunch length [mm]
300 44
Crossing angle [mrad] 20
Core beam size at IP horizontal sx* [nm]
639 45
Core beam size at IP vertical sy* [nm]
5.7
0.9
QD0, stabilisation
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CLIC09 - Machine Detector Interface

5. CLIC09 - Machine Detector Interface
MDI Priorities
Highest priority for the work until end 2010 are those subjects linked to the “CLIC critical feasibility items”, nota bene:
Choice of the magnet technology for the FF magnets
Integration of these magnets into the detectors, and their alignment
Feasibility study of sub-nm active stabilization of these magnets
Luminosity instrumentation
Spent beam disposal
Beam background backsplash from the post-collision collimators and dumps into the detector
Intrapulse-Beam feedback systems in the interface region
From the CLIC MDI working group mandate
L.Gatignon,
CLIC09 - Machine Detector Interface

6. Other items to be addressed in MDI:
Issues where the beam delivery system (BDS) influences the beam/background conditions for the detector
Issues where the BDS physically impacts on the detector
Beam background and its impact on the forward (det.+accel.) elements, including backsplash of background particles from one hardware element to the surrounding elements
Beam pipe, beam vacuum and vacuum infrastructure in the interface region
Radiation environment and radiation shielding in the interface region
Cryogenic operational safety issues in the interface region
Magnetic environment in the interface region (shielding of FF quadrupole, correction coils, anti(-DID), stray fields from the detector, etc.)
Overall mechanical integration (including the routing of services) in the interface region
Pull-push elements and scenarios (detector-to-detector interface)
Cavern layout and services (handled principally under CES WG)
From the CLIC MDI working group mandate
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CLIC09 - Machine Detector Interface

7. CLIC09 - Machine Detector Interface
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CLIC09 - Machine Detector Interface

8. CLIC09 - Machine Detector Interface
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CLIC09 - Machine Detector Interface

9. CLIC09 - Machine Detector Interface
Final Focus Quadrupole (QD0): Parameters
Parameter
Value
Gradient [T/m]
575
Length [m]
2.73
Aperture radius [mm]
3.83
Outer radius [mm] – for spent beam
< 50
Peak field [T]
2.20
Tunability of gradient from nominal
[-10%, 0%]
A conceptual design has recently been proposed by TE-MSC see presentation by M.Modena tomorrow
L.Gatignon,
CLIC09 - Machine Detector Interface

10. CLIC09 - Machine Detector Interface
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CLIC09 - Machine Detector Interface

12. CLIC09 - Machine Detector Interface
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CLIC09 - Machine Detector Interface

13. CLIC09 - Machine Detector Interface
QD0 Stabilisation
Any movement (vibration) of the QD0 quadrupole would lead to a deplacement of the beam at the IP comparable to the movement of the magnet
As the vertical spot size is about 1 nm, the quadrupole position must be stabilised to 0.15 nm in the vertical plane and 5 nm in the horizontal plane for frequencies > 4 Hz.
Beam-beam feedback will help.
A R&D program is under way for the stabilisation, based on passive and active stabilisation and cantilever based stabilisation.
The integration in the experiment (push-pull) is still an open issue. Studies are under way.
A review of stabilisation options is planned around the end of the year.
In case the L*=3.5 m (present baseline) option seems unrealistic, larger L* values may have to be considered for the CDR
See presentation by A.Jeremie in the parallel session tomorrow
L.Gatignon,
CLIC09 - Machine Detector Interface

14. Achieved performance The two first resonances entirely rejected
L.Brunetti et al (EPAC/Genova 2008)
Achieved performance
LAPP active system for resonance rejection
CERN TMC active table for isolation
The two first resonances entirely rejected
Achieved integrated rms of 0.13nm at 5Hz

15. Current work
Courtesy A.Jeremie
Replace big stabilisation table by a compact passive+active stabilisation system
Active system
Passive system
Instrumentation study (sensors and actuators)

16. Ex : force (actuator) applied to a point
Current work
Courtesy A.Jeremie
Simulations
Feedback development
Ex : force (actuator) applied to a point
Different strategies studied:
A knowledge only at strategic points
A local model for the disturbances amplified by eigenfrequencies.
A complete model
FF magnet design
Evgeny Solodko

17. From H.Schmickler
Under consideration

18. CLIC09 - Machine Detector Interface
QD0 Integration concept: first ideas
Courtesy A.Hervé
L.Gatignon,
CLIC09 - Machine Detector Interface

19. CLIC09 - Machine Detector Interface
Vibration measurements (e.g. recently in CMS cavern, with cooling off by Artoos, Guinchard) suggest once more that:
The QD0 quadrupole shall NOT be suspended from the detector
However, it must penetrate in the experiment to maintain peak luminosity
The QD0 supporting system must be strengthened (and shortened?)
Solutions may exist if opening the experiment on the IP is abandoned.
This implies that special efforts must be made in the machine and experiment, insulating e.g. rotating machines and water pipes mechanically
See presentation by A.Hervé tomorrow
L.Gatignon,
CLIC09 - Machine Detector Interface

20. CLIC09 - Machine Detector Interface
BDS/MDI IMPACT ON DETECTOR, BACKGROUNDS
Various effects occurring in the Beam Delivery System and Interaction Region impact significantly on luminosity, backgrounds and detector performance.
Effect
Consequences
How to deal with
Coherent pairs
Main background. Tails in CM energy
Blow-up, e+e+, e-e-
Spent beam
Crossing angle Detector design
Incoherent pairs
Backgrounds, e+e+, e-e-
Detector
gg  hadrons
Backgrounds, radiation
Horiz. beam size at IP
Neutrons from dumps
Background via backscattering through spent beam aperture
Masks? Dump design and location
Muons from collimation
Backgrounds, e.g. catastrophic Bremsstrahlung
Magnetic shielding
Solenoid field + crossing angle
Couples to beam, luminosity reduction
Anti-solenoid
Crab cavities
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CLIC09 - Machine Detector Interface

21. CLIC09 - Machine Detector Interface
Pair production - Spent beam line
Beam-beam interaction blows up & disrupts particles of opposite sign of main beam
Pair production limits the minimum radius of the vertex detector
Backscattering would cause serious background and radiation problems for the detector
Therefore particles leaving the IP at up to 10 mrad must be transported away cleanly
The energy contained in the outgoing beam is huge (14 MW) and must be dumped properly. A dump baseline design exists (ILC) but remains to be validated.
The spent beam lines also houses instrumentation for luminosity monitoring, the background conditions for these detectors must be optimised
Neutrons in the spent beam line and from the dumps remain to be simulated
See presentations in the parallel sessions
L.Gatignon,
CLIC09 - Machine Detector Interface

22. CLIC09 - Machine Detector Interface
Courtesy M.Battaglia and A.Sailer
Backscattered + direct pairs
Backscattered
pairs (not read)
Direct
pairs
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CLIC09 - Machine Detector Interface

24. E.Gschwendtner, EN/MEF

25. CLIC09 - Machine Detector Interface
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CLIC09 - Machine Detector Interface

26. CLIC09 - Machine Detector Interface
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CLIC09 - Machine Detector Interface

27. CLIC09 - Machine Detector Interface
gg  Hadrons
This process gives a particle density in the vertex detector which is only about a factor of 4 lower than the background from incoherent pairs:
Courtesy M.Battaglia and D.Schulte
L.Gatignon,
CLIC09 - Machine Detector Interface

28. 850 tracks reconstructed by local pattern recognition
50 Bunch crossings of gg  hadrons background in the vertex detector
850 tracks reconstructed by local pattern recognition
Courtesy M.Battaglia
L.Gatignon,
CLIC09 - Machine Detector Interface

29. CLIC09 - Machine Detector Interface
e⁺ + e⁻ → χ⁺ + χ⁻ → χ⁰ + χ ⁰ + W ⁺ W ⁻
Without γ γ
Idem with 20 Bx
γ γ → hadrons
pile up.
The background may spoil the jet energy resolution and affect discrimination variables e.g missing energy, Θ ,....
But low E, Pt particles.
Courtesy JJ.Blaising
L.Gatignon,
CLIC09 - Machine Detector Interface

30. CLIC09 - Machine Detector Interface
Muons from beam halo
Beam tails are scraped away by a collimation system in the BDS.
Below we show simulated profiles of the beam at the BDS entrance (core of beam in red)
From I.Agapov et al, 2009, to be published
From these simulations one estimates that a fraction hit the collimators, i.e. about particles per train assuming a total flux of per train.
Preliminary estimates indicate that out of those ~ would reach the detectors.
The final rates remain to be studied with BDSIM using the final and detailed geometry
See presentation by H.Burkhardt in BDS parallel session
L.Gatignon,
CLIC09 - Machine Detector Interface

31. CLIC09 - Machine Detector Interface
ANTI-SOLENOID, ANTI-DID
In the presence of a crossing angle, the beam couples to the longitudinal field of the main detector solenoid.
The solenoid field would also affect the long-term stability of the permanent magnets in the QD0 quadrupole.
A proposal has been made for a compensating solenoid around the QD0 quadrupole See presentation tomorrow by B.Dalena
Its mechanical design, integration in the detector and impact on the QD0 stabilisation remains to be studied
The anti-DID effect has been simulated, in particular its impact on the luminosity See presentation tomorrow by B.Dalena
L.Gatignon,
CLIC09 - Machine Detector Interface

33. CLIC09 - Machine Detector Interface
Intra-Pulse Feedback
Summary of latency times of different FONT tests:
Note: 23 ns is the TOTAL latency time: 10 ns (tof + signal return time)
plus 13 ns (electronics)
Scales with distance
(Almost) invariant
Latest status will be reported by J.Resta Lopez
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CLIC09 - Machine Detector Interface

34. Cavern Layout
Courtesy J.Osborne
Based on ILC design

35. CLIC09 - Machine Detector Interface
Cavern layout
A. Hervé – H. Gerwig – A. Gaddi / CERN
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CLIC09 - Machine Detector Interface

36. CLIC09 - Machine Detector Interface
Detector moving
Air-pads at CMS – move 2000T
Concept of the platform, A.Herve, H.Gerwig
J.Amann
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CLIC09 - Machine Detector Interface

37. CLIC09 - Machine Detector Interface
Summary and Conclusions
The Machine Detector Interface region is full of challenges: - QD0 quadrupole - Its stabilisation and integration - Intra-pulse feedback system - Backgrounds - Handle the beam power of the spent beam - Vacuum - Civil engineering and services - ……..
Work is going on enthusiastically to cope with these challenges towards a plausible solution for the CDR
More details in the parallel sessions
Thanks to the colleagues in the MDI group for their input
L.Gatignon,
CLIC09 - Machine Detector Interface